Industrial manufacturing of a garment currently requires an inordinate amount of time to handle material that will eventually comprise a garment. In excess of 80% of the time spent on any one garment may go to material handling. Sewing, for example, represents a surprisingly small proportion of manufacturing time, relative to handling. One area of the process that is particularly time-consuming is separation of a stack of fabric workpieces to allow easy subsequent handling of individual workpieces.
A workpiece stack can be created by repeatedly folding a piece of fabric onto itself and then cutting a single pattern clear through all layers of the multiple-folded cloth. This produces a stack comprised of flexible planar objects of uniform size, oriented such that all edges of each object are juxtaposed with the corresponding edges of each immediately adjacent object. This arrangement produces a stack with ends defined by the two outermost planar objects, and sides defined by the juxtaposed edges of the several juxtaposed objects, which sides are all approximately perpendicular to the two parallel planes containing the end members of the stack.
By automating the process by which such stacks are separated, increased efficiency in handling fabric workpieces can be obtained. However, numerous difficulties are encountered in attempting to automate the separation of flexible planar objects. Unlike the rigid planar objects to which much of the prior art is addressed, stacks of flexible objects easily lose a workable shape if their movement is not strictly controlled. Thus, flexible objects cannot be expected to "fall into place" of their own accord, a characteristic upon which art such as U.S. Pat. Nos. 4,008,890 (PULDA) and 4,049,259 (VENTZ) depends.
Much of the prior art also relies on minimal cohesion between juxtaposed planar surfaces. Where the planar objects are characterized by more substantial coefficients of friction, however, individual sheets are more likely to clump together, resisting current methods of separation. Although some of the art has addressed the "clumping" contingency, it does so only on an "as needed" basis.
It is an object of the present invention to prepare stacks of flexible planar objects for subsequent automated separation by shingling the stack. Once the stack is shingled, an edge of each individual workpiece is exposed for easier handling. A further objective is to carry out this function in a manner which at all times controls the stack such that neither the stack nor the flexible planar objects composing said stack lose a workable shape. Additionally, the present invention is designed to prevent clumping entirely so that special time-consuming measures to separate clumps are avoided. Additional objectives, advantages and features of the present invention are explained as part of the following detailed description.